1. Field of the Invention
The present invention relates to fire retardant intumescent coating compositions which are employed as adhesive materials for the lamination of plastic film support backing to insulation battings.
2. Description of the Prior Art
Numerous patents and literature references exist in the field of fire retardant compounds and compositions useful as additives and/or coatings for films, including polyolefin films such as polyethylene, polypropylene, polybutene and the like. Such prior art fire retardant materials are generally extremely costly and are usually tailored to treat the effects and contain flame propagation rather than to eliminate the cause of the fire propagation.
When thin flexible film of polyolefins are ignited, the film shrinks away from the applied flame at a rate faster than the flame front velocity and thus appears to be self-extinguishing. However, with continued flame application, olefins become molten and drop and thus support flame. When polyolefins are used in laminar constructions, e.g., as backing material for insular battings such as fiber glass batting, the adhesive which bonds the film to the batting prevents the film from shrinking away from a flame front and the flame is readily propagated. Additionally, the heated polyolefin becomes molten and wicks into the batting layer thereby spreading the combustion.